The easiest way to reset the resolution correctly is to borrow another monitor and temporarily hook it up to the mini. Set generic display preferences on the borrowed monitor and then shut down. Attach the Panasonic and see what happens. You can always readjust the display preferences once the Panasonic is working.

If that doesn't seem to work, it may be that the Panasonic is not being detected correctly. It's possible your mini's graphic signal is over scanning which would shut the Panasonic down to prevent damage.